Conventionally, a user of a database searches for desired data by inputting a keyword (i.e., a string of characters) that is utilized for extraction of the data from the database. The number of keywords may be only one word, or may be plural number of words depending on a situation. When the plural number of words are used for data search, the data is searched by either matching all of the keywords (AND search) or matching one or more of the plural keywords (OR search). The search may also performed by combining the AND search and the OR search. The search method described above is, for example, disclosed in Japanese patent document JP-A-H05-128153.
The AND search combines the plural keywords by using “AND” or “&.” In this case, the keywords input looks like “XXX AND YYY” or “XXX & YYY.”
Some of the vehicle navigation systems search for a destination or the like by using a search method with the AND search capability (e.g., an enhanced search function) for facilitating the destination search by a user who does not have a clear memory of, for example, a previously visited place. The search method utilizes the AND search capability to easily find the visited place by combining plural keywords of place name and a restaurant category. That is, the destination may be search for by inputting “Washington D.C.” together with a restaurant category of “Chinese” or the like.
The AND search may be performed, in some cases, by “combining” the plural keywords by the space. That is, in other words, some of the databases implement the AND search capability in a format that combines plural keywords separated by spaces in the keyword input instead of using “AND,” or “&,” or other expressions.
However, when the keywords looks, for example, like “A MART” for the data search of a shop having a name “A,” the data search function in the database may falsely determine that the user likes to perform the AND search by using both of the keywords “A” and “MART.” When the data search is performed with a very short keyword string or the like, the search result may list a large number of searched items to be scrolled through again, or the search itself may take a very long time due to a huge amount of data that fulfills the AND condition of the short keywords.